ARM: sunxi: dt: Convert to the new net compatibles

Switch the device tree to the new compatibles introduced in the ethernet and
mdio drivers to have a common pattern accross all Allwinner SoCs.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>